Fix the issue with interning of types in the SoN backend

seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/Compiler.java

@@ -60,7 +60,7 @@ public class Compiler {
     // Mapping from a type name to a Type.  The string name matches
     // `type.str()` call.  No TypeMemPtrs are in here, because Simple does not
     // have C-style '*ptr' references.
-    public static HashMap<String, Type> TYPES = new HashMap<>();
+    private final HashMap<String, Type> types = new HashMap<>();
 
     private ArrayList<Node> ctorStack = new ArrayList<>();
 
@@ -70,10 +70,9 @@ public Compiler(CodeGen codeGen, TypeInteger arg) {
 
     public void parse() {
         this.typeDictionary = createAST(_code._src);
-        Map<String, Type> types = new HashMap<>();
+        types.clear();
         populateDefaultTypes(types);
         populateTypes(types);
-        TYPES.putAll(types);
         ZERO  = con(TypeInteger.ZERO).keep();
         NIL  = con(Type.NIL).keep();
         XCTRL= new XCtrlNode().peephole().keep();
@@ -269,7 +268,7 @@ private void defineScopedVars(Scope scope, ScopeNode scopeNode, FunNode fun) {
         for (Symbol symbol: scope.getLocalSymbols()) {
             if (symbol instanceof Symbol.VarSymbol varSymbol) {
                 varSymbol.regNumber = REGNUM++;
-                Type sonType = TYPES.get(varSymbol.type.name());
+                Type sonType = types.get(varSymbol.type.name());
                 if (sonType == null)
                     throw new CompilerException("Unknown SON Type "+varSymbol.type.name());
                 Node init = null;
@@ -290,7 +289,7 @@ private void generateFunction(Symbol.FunctionTypeSymbol functionTypeSymbol) {
         ctrl(XCTRL);
         _scope.mem(new MemMergeNode(false));
 
-        var funType = (TypeFunPtr) TYPES.get(functionTypeSymbol.name);
+        var funType = (TypeFunPtr) types.get(functionTypeSymbol.name);
         if (funType == null) throw new CompilerException("Function " + functionTypeSymbol.name + " not found");
 
         // Parse whole program, as-if function header "{ int arg -> body }"
@@ -612,11 +611,11 @@ private Node newStruct(TypeStruct obj, Node size) {
     private Node compileNewExpr(AST.NewExpr newExpr) {
         EZType type = newExpr.type;
         if (type instanceof EZType.EZTypeArray typeArray) {
-            TypeMemPtr tarray = (TypeMemPtr) TYPES.get(typeArray.name());
+            TypeMemPtr tarray = (TypeMemPtr) types.get(typeArray.name());
             return newArray(tarray._obj,newExpr.len==null?ZERO:compileExpr(newExpr.len));
         }
         else if (type instanceof EZType.EZTypeStruct typeStruct) {
-            TypeMemPtr tptr = (TypeMemPtr) TYPES.get(typeStruct.name());
+            TypeMemPtr tptr = (TypeMemPtr) types.get(typeStruct.name());
             return newStruct(tptr._obj,con(tptr._obj.offset(tptr._obj._fields.length)));
         }
         else
@@ -703,7 +702,7 @@ else if (constantExpr.type instanceof EZType.EZTypeNull)
 
     private Node compileSymbolExpr(AST.NameExpr symbolExpr) {
         if (symbolExpr.type instanceof EZType.EZTypeFunction functionType)
-            return con(TYPES.get(functionType.name));
+            return con(types.get(functionType.name));
         else {
             Symbol.VarSymbol varSymbol = (Symbol.VarSymbol) symbolExpr.symbol;
             Var v = _scope.lookup(makeVarName(varSymbol));

seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/Var.java

@@ -2,7 +2,6 @@
 
 import com.compilerprogramming.ezlang.compiler.type.*;
 
-
 /**
  *  The tracked fields are now complex enough to deserve a array-of-structs layout
  */
@@ -27,10 +26,8 @@ public Var(int idx, String name, Type type, boolean xfinal, boolean fref) {
         _fref = fref;
     }
     public Type type() {
-        if( !_type.isFRef() ) return _type;
-        // Update self to no longer use the forward ref type
-        Type def = Compiler.TYPES.get(((TypeMemPtr)_type)._obj._name);
-        return (_type=_type.meet(def));
+        assert !_type.isFRef();
+        return _type;
     }
 
     // Forward reference variables (not types) must be BOTTOM and

seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/codegen/CodeGen.java

@@ -43,6 +43,7 @@ public enum Phase {
     // ---------------------------
     public CodeGen( String src ) { this(src, TypeInteger.BOT, 123L ); }
     public CodeGen( String src, TypeInteger arg, long workListSeed ) {
+        Type.resetInternTable();
         CODE = this;
         _phase = null;
         _callingConv = null;
@@ -51,6 +52,7 @@ public CodeGen( String src, TypeInteger arg, long workListSeed ) {
         _src = src;
         _arg = arg;
         _iter = new IterPeeps(workListSeed);
+        _main = makeFun(TypeTuple.MAIN, Type.BOTTOM);
         P = new Compiler(this,arg);
     }
 
@@ -141,7 +143,7 @@ public TypeFunPtr makeFun2(TypeTuple sig, Type ret ) {
         return new TypeFunPtr((byte)2,sig,ret, 1L<<fidx );
     }
     // Signature for MAIN
-    public TypeFunPtr _main = makeFun(TypeTuple.MAIN, Type.BOTTOM);
+    public TypeFunPtr _main;
     // Reverse from a constant function pointer to the IR function being called
     public FunNode link( TypeFunPtr tfp ) {
         assert tfp.isConstant();

seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/type/Type.java

@@ -81,6 +81,24 @@ public static Type[] gather() {
         return ts.toArray(new Type[ts.size()]);
     }
 
+    private static HashMap<Type, Type> INTERN_BASELINE;
+
+    /**
+     * Call this at the start of each front-end compilation
+     * run to reset the intern table to core types that the SoN backend
+     * needs. The reset drops any types added by a previous
+     * compile run.
+     */
+    public static void resetInternTable() {
+        if( INTERN_BASELINE == null ) {
+            gather();
+            INTERN_BASELINE = new HashMap<>(INTERN);
+        } else {
+            INTERN.clear();
+            INTERN.putAll(INTERN_BASELINE);
+        }
+    }
+
     // Is high or on the lattice centerline.
     public boolean isHigh       () { return _type==TTOP || _type==TXCTRL || _type==TXNIL; }
     public boolean isHighOrConst() { return isHigh() || isConstant(); }

seaofnodes/src/test/java/com/compilerprogramming/ezlang/compiler/TestSONTypes.java

@@ -170,6 +170,24 @@ func foo()->Int {
         compileSrc(src);
     }
 
+    @Test
+    public void testStructLayoutsDoNotLeakAcrossCompilations() {
+        compileSrc("""
+struct Point { var x: Int }
+func foo()->Int {
+  var p = new Point { x = 1 }
+  return p.x
+}
+""");
+        compileSrc("""
+struct Point { var y: Int }
+func foo()->Int {
+  var p = new Point { y = 2 }
+  return p.y
+}
+""");
+    }
+
     @Ignore("Bug in backend")
     @Test
     public void testArrayLoadNullCheckNarrowsNullableElement() {